Scientist stumbles on new class of living things

London: A scientist claims to have discovered not just a new species but a whole new branch of the tree of life.

Living things are currently split into three domains, eukaryotes, or complex celled organisms such as animals, plants and humans and two simple celled micro-organism divisions - bacteria and archaea.

But now Prof Jonathan Eisen, evolutionary biologist at the University of California, working with the lab of the maverick scientist Craig Venter, claims to have discovered the fourth, the journal Public Library of Science reports.

Prof Eisen stumbled on variations of two genes called RecA and RpoB, both of which are old and abundant, which did not fit into any of the three existing domains, according to a newspaper report.

Prof Eisen used complicated gene sequencing techniques to look at DNA collected by Venter on a round the world yachting trip,

"They could represent an unusual virus, which is interesting enough. More interestingly still, they could represent a totally new branch in the tree of life," he said.

"Even though we did not have the story completely pinned down, we decided to finally write up the paper to get other people to think about this issue," added Prof Eisen.

One of the difficulties of trying to study novel genes is that it is hard to culture them to such a quantity to make them easily readable. Prof Eisen used methods honed by Venter in his successful attempt to read the human genetic code.

They have dubbed the technique as "metagenomics" and it involves breaking down the DNA to sizeable chunks, decoding them and then reassembling in the correct order.

The science benefits greatly from ever more powerful and cheaper computers. The team applied the technique to seawater samples collected between 2003 and 2007 from the world`s oceans by Venter on his yacht, Sorcerer II.